Black storks fly over Miyun Reservoir in Beijing, capital of China, Oct. 28, 2017. Several endangered black storks (Ciconia nigra) were spotted at Miyun Reservoir, signaling improvement in the reservoir environment. Black storks are on the red list of threatened species by the International Union for Conservation of Nature. There are only about 2,000 such birds in the world. (Xinhua/Wang Zhiyi)